Is your business suffering with an inefficient central heating system such as radiators that don’t heat up properly or unexplained noises? Perhaps you need to keep replacing boiler parts?

If so, the chances are you could have a buildup of sludge.

What is sludge?

Magnetite, commonly referred to as sludge, is the black substance comprising dissolved and rusted metal from the pipework of your central heating system.

It forms when air and water react with ferrous components – for instance, the water within the system reacts with the steel inside your radiators.

Because magnetite is heavier than water, it often settles in the radiators and pipework on lower levels, such as ground floors and basements. If left to build up, it can have devastating effects on the boiler and the system.

Symptoms of sludge build up

Knowing the signs of magnetite in your system can help save you costs, downtime and stress.

Common signs of sludge include:

  • Radiators which are hot at the top but cold at the bottom
  • Radiators requiring bleeding more frequently
  • Pipework to the radiators getting hot, but not the radiators themselves
  • Some radiators failing to reach the required temperature, even when the temperature is turned up
  • The boiler pump leaking or failing
  • When boiler parts are removed/replaced, they are full of dirt
  • The flow is boiling hot but the return is lukewarm or cold
  • A noisy system including gurgling and kettling
  • Higher energy bill

Effects of sludge build up

If sludge is allowed to build up, it can restrict the flow of water through pipework as it begins to block the pipe. This can be particularly expensive to fix if it blocks the pipes on the heat exchanger.

While many new commercial boilers have heat exchangers with narrow pipes to allow for better efficiency, it’s a double edged sword. The narrow pipes also makes them more vulnerable to blockages, and if affected by sludge, the heat exchanger could need replacing.

Magnetite in your system escalates problems which can result in radiators, parts or even entire boilers needing to be replaced. A blocked boiler will overheat, causing it to shut down completely.

The common effects of sludge include:

  • Damage to the boiler
  • Damage to the boiler pump
  • Damage to radiators, including leaks
  • Damage to radiator valves
  • Blocked pipework, including on the heat exchanger
  • Higher energy bills


All heating systems are at risk from magnetite, but there are precautions you can take to help reduce it. If left untreated, a build-up of sludge will lead to higher energy bills, premature failure of components and even complete boiler failure in extreme circumstances.

Boiler failure due to sludge can cause a massive headache for any business and could even lead to a shutdown. Regular servicing and maintenance is essential, but in the event of a shutdown, whether planned or unexpected, commercial boiler hire can keep everything going until the problem is fixed. Here at Ideal Heat Solutions we’re dedicated to keeping your business up and running during scheduled maintenance or in an emergency. If you’d like to know more, contact us and find out how temporary boiler hire can solve your problems.